Many nuclear imaging procedures are currently limited by the bulk, cost, complexity and fragility of scintillation cameras, which employ large NaI crystals and large banks of photomultiplierr tubes. We propose to develop a gamma camera based on xeron gas proportional tubes oriented parallel to incident radiation and operated at high pressure. In pilot studies, high quality proportional gas response has been achieved to 20 atm pressure with such tubes. Therefore, optimal stopping power and imaging characteristics can be achieved for Tl-201 and the short-lived Ta-178 (9.3 min) generator-produced isotope, which is currently undergoing FDA trials. This Phase I project will investigate the feasibility of developing a tube capable of efficient imaging of Tc-99m. Pending the outcome of this feasibility study, Phase II will be directed either towards development of Tc-99m imaging device or towards the more modest objective of a 20 atmosphere device. The latter technology would provide a means of obtaining both angiographic and perfusion imaging in the bedside intensive care setting and thereby provide a full range of nuclear capabilities in this setting for early evaluation of myocardial infarction and for assessment of post-intervention patients. PROPOSED COMMERCIAL APPLICATION This technology addresses a serious need in the cardiology field. Current nuclear cameras are far too bulky and immobile to function at the bedside in the intensive care setting. A device satisfying this need will be developed which will provide a full spectrum of cardiac evaluation in this setting. There are approximately a half million myocardial infarctions annually in the U.S. and comparable numbers of post-surgery and angioplasty patients who could benefit from such technology. Expansion of this technology to successful imaging of Tc-99m would open a much more sizable market opportunity.